Radio communication system, method, program, base station apparatus, multi-cell/multicast cooperation control apparatus

ABSTRACT

Disclosed is a radio communication system in which transmission parameters, such as MCS of MBSFN, the number of subframes, and a transmission power of a reserved cell, are adaptively output, based on a unicast traffic volume in a MBSFN area, a number of terminals, and a number of cells of the MBSFN area, so that a system throughput in the MBSFN area is maximized while satisfying an MBSFN quality requirement condition.

TECHNICAL FIELD Reference to Related Application

This application is based upon and claims the benefit of the priority ofJapanese patent application No. 2008-172798 filed on Jul. 1, 2008, thedisclosure of which is incorporated herein in its entirety by referencethereto.

The present invention relates to a radio communication system thatperforms an MBSFN (Multimedia Broadcast Multicast Service SingleFrequency Network or Multicast/Broadcast over Single Frequency Network)transmission and a unicast transmission, and more particularly to aradio communication system in which two types of area, an area where anMBSFN transmission is performed and an area where a unicast transmissionis performed at the same time an MBSFN transmission is performed, aremixed in an area in which MBSFN is supported.

BACKGROUND

In 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution),it has been decided to support MBSFN in which multiple base stations aresynchronized to perform MBMS (Multimedia Broadcast and MulticastService) on the same frequency.

An MBSFN area (range in which multiple base stations are synchronized toperform the same MBSFN transmission) defined by LTE is composed of thefollowing two types of cells (Non-Patent Document 1):

-   -   Cell in which a base station performs an MBSFN transmission        (MBSFN transmitting and advertising cell: hereinafter termed an        “MBSFN service cell”); and    -   Cell in which a base station does not contribute to an MBSFN        transmission, but performs only a unicast or        single-cell/multicast transmission is performed (MBSFN area        reserved cell: hereinafter termed a “reserved cell”).

Note that the terms MBSFN, unicast, and multicast include not onlycommunications using MBSFN, unicast, and multicast respectively but alsoservices using MBSFN, unicast, and multicast respectively.

Unicast transmission and MBSFN transmission are time-divisionmultiplexed (TDM) on a per-subframe basis. For example, when tensubframes make up one frame and there are four MBSFN subframes, theremaining six subframes are unicast subframes.

In an MBSFN service cell, the subframes other than MBSFN subframes(subframes used for MBSFN transmission) are unicast subframes.

In a reserved cell, one of the following two types of control isperformed when multiple other cells in the MBSFN area perform MBSFNtransmission (MBSFN subframe transmission time period).

Decrease the transmission power and perform unicast transmission (forexample, unicast transmission only to the terminals in the center of thecell is performed) or perform single-cell/multicast transmission; and

Do not transmit any data.

One of the purposes of this reserved cell, provided on the boundary withother MBSFN areas or unicast cells, is to reduce interference fromoutside the MBSFN area and to improve coverage and outage of MBSFN.

The transmission power or the maximum of the transmission power in areserved cell is determined by the target value of the MBSFN outage andthe MBSFN MCS (Modulation and coding Scheme) using, for example, a table(decision table) that is prepared in advance.

Note that an outage represents that a user does not satisfy a servicerequirement condition of a communication system and corresponds, forexample, to a service condition that is equal to or lower than an outagethreshold of an acceptable performance of the system. This outagethreshold is the minimum performance index at which the system isconsidered to be in an operating state. For example, when a requirederror rate outage, that is, an outage probability, is used, whether ornot a percent of users whose required error rate exceeds the outageprobability is lower than x % (for example, 5%) of entire users is acriterion at which the system is judged to be in the normal operatingstate.

With reference to FIG. 24 and FIG. 25, a conventional method fordetermining a transmission power, or the maximum of the transmissionpower, of a base station in a reserved cell using a table prepared inadvance will be described. As shown in FIG. 24, it is assumed that thereis an MBSFN area that is composed of MBSFN service cells and reservedcells and that the MBSFN area is surrounded by neighboring unicastcells.

FIG. 25 is a diagram showing an example of a table used to determine thetransmission power, or the maximum of the transmission power, of areserved cell. As shown in FIG. 25, the relation (correspondence) amongthe outage probability (%) of the MBSFN required error rate, MCS, andthe transmission power, or the maximum of the transmission power, of abase station in a reserved cell is prepared in the memory as a table.The values of the table shown in FIG. 25 have been calculated in advancethrough computer simulation.

First, the following describes how to interpret the table in FIG. 25.Although not limited thereto, it is known in the radio communicationthat the smaller the MBSFN MCS number is, the lower a modulation rateand a coding rate are and that the larger the number is, the higher themodulation rate and the coding rate are. For example, MCS 1 correspondsto QPSK (Quadrature Phase Shift Keying) and MCS 10 corresponds to 16QAM(Quadrature Amplitude Modulation).

When the transmission power, or the maximum of the transmission power,of a base station in a reserved cell is 100% (the ratio of thetransmission power to the transmission power of an MBSFN subframe is100%, and this is the maximum transmission power), the outageprobability for MBSFN MCS 1 is 20% (20 terminals out of 100 terminalscannot receive MBSFN). The outage probability (%) is 40% for MBSFN MCS2, and this corresponds to a situation in which 40 terminals out of 100terminals cannot receive MBSFN. The outage probability (%) is 100% forMBSFN MCS 10, and this corresponds to a situation in which 100 terminalsout of 100 terminals cannot receive MBSFN.

When the transmission power, or the maximum of the transmission power,of a base station in a reserved cell is reduced to 50%, the outageprobability for MBSFN MCS 1 is 10% (10 terminals out of 100 terminalscannot receive MBSFN). The outage probability for MBSFN MCS 2 (%) is20%, and this corresponds to a situation in which 20 terminals out of100 terminals cannot receive MBSFN. The outage probability (%) for MBSFNMCS 10 is 80%, and this corresponds to a situation in which 80 terminalsout of 100 terminals cannot receive MBSFN.

When the power of a base station in a reserved cell is 0% (no datatransmission), the outage probability for MBSFN MCS 1 is 0% (That theMBSFN outage probability (%) is 0% means that the percent of users(terminals) who cannot receive MBSFN is 0%). The outage probability (%)for MBSFN MCS 2 is 2%, and this corresponds to a situation in which twoterminals out of 100 terminals cannot receive MBSFN. When the power of abase station in a reserved cell is 0% for MBSFN MCS 10, the outageprobability (%) is 10% and this corresponds to the state in which tenterminals out of 100 terminals cannot receive MBSFN.

The MBSFN outage probability is determined based on the requirementcondition for the quality of MBSFN that is actually transmitted, and,based on a volume of PTP (Point To Point) traffic in the reserved cell,the following are determined:

-   -   MBSFN MCS satisfying an outage probability; and    -   Transmission power, or the maximum of transmission power, for        MBSFN subframes in a reserved cell (percent of MBSFN power) Note        that PTP, which is equivalent to unicast, means a dedicated        communication scheme or a service by the dedicated communication        scheme.

For example, if

the number of MBSFN subframes is fixed,

the target value of MBSFN outage probability is 10%, and

MCS is 2,

then, it is determined by the table in FIG. 25 that the transmissionpower, or the maximum of the transmission power, of a base station inthe reserved cell is 10% of the maximum transmission power of MBSFN.

On the other hand, if a transmission rate of MBSFN is fixed, the numberof MBSFN subframes is changed so that the number is inverselyproportional to the MBSFN MCS value (normally, the smaller the value is,the lower the rate). When the MBSFN MCS value is small, the number ofMBSFN subframes per frame is increased.

Non-Patent Document 1:

-   3GPP TSG RAN WG2, Stage 2 specification 36.300 v8 3.0    http://www.3gpp.org/ftp/Specs/html-info/36300.htm

SUMMARY

The disclosure of Non-Patent Document 1 given above is herebyincorporated in its entirety by reference into this specification. Thefollowing analysis is given by the present invention. The followinggives an analysis of the related technologies of the present invention.

In the related art described above, the power of a base station in areserved cell is set according to the pre-set table indicating therelation among the target values of MBSFN outage target probability,MBSFN MCS, and the transmission power, or the maximum of thetransmission power, of a base station in a reserved cell. Therefore,only the quality of MBSFN is considered, but not the quality ofnon-MBSFN. This may have an effect on the quality or the capacity ofnon-MBSFN.

It is an object of the present invention to provide a radiocommunication system, a base station apparatus, a Multi-cell/MulticastCoordination Entity (MCE), a radio communication method, and a programthat allow setting to be optimally determined from the viewpoint of PTP(point-to-point) system throughput in an MBSFN area while satisfying arequirement for a MBSFN quality.

According to the present invention, there is provided a system (method,program) which receives communication status information from all or apart of a plurality of radio stations, and outputs communication controlinformation for use in multicasting by a plurality of radio stations.

According to the present invention, there is provided a system (method,program) which receives the communication status information from aplurality of radio stations in an MBSFN area, and outputs thecommunication control information in the MBSFN area, the MBSFN areabeing an applicable range of MBSFN (Multimedia Broadcast MulticastService Single Frequency Network) in which a plurality of radio stationsare synchronized to transmit the same content on the same frequency atthe same time.

According to the present invention, there is provided a base stationapparatus that includes an MBSFN (Multimedia Broadcast Multicast ServiceSingle Frequency Network) function that causes the base stationapparatus to synchronize with one or more other base station apparatusesto transmit the same content on the same frequency at the same time; anda unicast function, characterized in that the base station apparatusnotifies a Multi-cell/Multicast Coordination Entity (MCE) aboutcommunication status information and receives communication controlinformation from the Multi-cell/Multicast Coordination Entity to performMBSFN transmission or unicast or single-cell/multicast transmission.

According to the present invention, there is provided aMulti-cell/Multicast Coordination Entity (MCE) apparatus that outputscommunication control information on MBSFN (Multimedia BroadcastMulticast Service Single Frequency Network) in which a plurality of basestation apparatuses are synchronized to transmit the same content on thesame frequency at the same time, characterized in that theMulti-cell/Multicast Coordination Entity (MCE) apparatus receivescommunication status information from a base station apparatus in anMBSFN area, which is an applicable range of MBSFN, and notifies the basestation apparatus about the communication control information.

In the present invention, the Multi-cell/Multicast Coordination Entity(MCE) apparatus may adaptively output transmission parameters, such asthe MCS of MBSFN, the number of MBSFN subframes, and a transmissionpower of a base station apparatus in a reserved cell, so that a systemthroughput of an MBSFN area is maximized while satisfying an MBSFNquality requirement condition and based on a unicast traffic volume ofthe MBSFN area, the number of terminals, and the number of cells of theMBSFN area.

According to the present invention, a PTP (Point-to-Point) systemthroughput of an MBSFN area may be maximized while satisfying an MBSFNquality requirement condition. Still other features and advantages ofthe present invention will become readily apparent to those skilled inthis art from the following detailed description in conjunction with theaccompanying drawings wherein only exemplary embodiments of theinvention are shown and described, simply by way of illustration of thebest mode contemplated of carrying out this invention. As will berealized, the invention is capable of other and different embodiments,and its several details are capable of modifications in various obviousrespects, all without departing from the invention. Accordingly, thedrawing and description are to be regarded as illustrative in nature,and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a first configuration example of a radiocommunication network apparatus in the present invention.

FIG. 2 is a diagram showing a first example of the sequence diagram inthe present invention.

FIG. 3 is a diagram showing a second configuration example of a radiocommunication network apparatus in the present invention.

FIG. 4 is a diagram showing a second example of the sequence diagram inthe present invention.

FIG. 5 is a diagram showing a third configuration example of a radiocommunication network apparatus in the present invention.

FIG. 6 is a diagram showing the concept of control in the presentinvention.

FIGS. 7A and 7B are diagrams showing PTP traffic volumes used in thepresent invention.

FIG. 8 is a diagram showing an example of the configuration of an MBSFNarea in an embodiment of the present invention.

FIGS. 9A-9E are diagrams showing an example of transmission parametercontrol in an MBSFN area in the embodiment of the present invention.

FIGS. 10A-10E are diagrams showing an example of transmission parametercontrol in an MBSFN area in the embodiment of the present invention.

FIG. 11 is a diagram showing an example of the configuration of an MBSFNarea in first and second exemplary embodiments of the present invention.

FIGS. 12A-12I are diagrams showing an example of transmission parametercontrol in an MBSFN area in the first and second exemplary embodimentsof the present invention.

FIG. 13 is a block diagram showing a base station in the first andsecond exemplary embodiments of the present invention.

FIGS. 14A and 14B are flowcharts showing the processing of the basestation in the first exemplary embodiment of the present invention.

FIG. 15 is a block diagram showing an MCE in the first exemplaryembodiment of the present invention.

FIG. 16 is a flowchart showing the processing of the MCE in the firstexemplary embodiment of the present invention.

FIG. 17 is a diagram showing a table used to determine transmissionparameters for an MBSFN area in the first exemplary embodiment of thepresent invention.

FIG. 18 is a diagram showing a table used to determine transmissionparameters for an MBSFN area in the first exemplary embodiment of thepresent invention.

FIGS. 19A and 19B are diagrams showing a change in the PTP trafficvolume over time used to determine transmission parameters for an MBSFNarea, and the transmission parameters for the MBSFN area determinedbased on the change, in the first exemplary embodiment of the presentinvention.

FIG. 20 is a block diagram showing an MCE in the second exemplaryembodiment of the present invention.

FIG. 21 is a flowchart showing the processing of the MCE in the secondexemplary embodiment of the present invention.

FIG. 22 is a diagram showing a table used to determine transmissionparameters for an MBSFN area in the second exemplary embodiment of thepresent invention.

FIG. 23 is a diagram showing a table used to determine transmissionparameters for an MBSFN area in the second exemplary embodiment of thepresent invention.

FIG. 24 is a diagram showing an example of cell arrangement of an MBSFNarea used to describe a related technology.

FIG. 25 is a diagram showing a table used to determine transmissionparameters for an MBSFN area in the related technology.

PREFERRED MODES

In the present invention, communication status information is receivedfrom a plurality of radio stations in an MBSFN area and communicationcontrol information in the MBSFN area is output, the MBSFN area being anapplicable range of MBSFN (Multimedia Broadcast Multicast Service SingleFrequency Network) in which a plurality of radio stations aresynchronized to transmit the same content on the same frequency at thesame time.

In the present invention, the MBSFN area includes

a radio station that performs both MBSFN transmission and unicasttransmission, and

a radio station that does not contribute to MBSFN transmission. In thepresent invention, the communication control information for MBSFNtransmission by the radio station that is in the MBSFN area and thatperforms MBSFN transmission, and the communication control informationfor a communication by the radio station that is in the MBSFN area butthat, when MBSFN transmission is performed in the MBSFN area, does notcontribute to the MBSFN transmission are output.

In the present invention, the communication status information includesat least one of

system component information,

multicast related information, and

unicast related information. In the present invention, the communicationcontrol information includes at least one of

a transmission parameter for the MBSFN area and

a cell type of each cell belonging to the MBSFN area. In the presentinvention, the communication control information is output so that anMBSFN requirement condition is satisfied. If multiple levels are set forthe requirement condition, the communication control information isoutput so that at least the lowest-level requirement condition issatisfied.

In a radio communication system, a base station apparatus, and aMulti-cell/Multicast Coordination Entity (MCE) provided by the presentinvention, a transmission parameter for an MBSFN subframe in an MBSFNarea is adaptively output based on at least one of

the number of base stations that perform MBSFN transmission,

the number of areas served by a base station that performs MBSFNtransmission,

a size of an area served by a base station that performs MBSFNtransmission,

the number of base stations that do not contribute to MBSFNtransmission,

the number of areas (cells) served by a base station that does notcontribute to MBSFN transmission, and

a size of an area (cell) served by a base station that does notcontribute to MBSFN transmission,

each of which is system component information in an MBSFN area,

and/or,

at least one of

the number of terminals that are receiving MBSFN transmission orinformation that makes it possible to estimate the number of saidterminals,

the number of terminals that want to receive MBSFN transmission orinformation that makes it possible to estimate the number of saidterminals,

a quality (error rate) of MBSFN transmission being executed orinformation that makes it possible to estimate the quality, and

a ratio between the number of terminals that are receiving MBSFNtransmission and the number of terminals that are receiving unicasttransmission

each of which is multicast related information,

and/or,

at least one of

a unicast traffic volume (load),

the number of terminals that are receiving unicast transmission,

the number of terminals in an active state that may receive unicasttransmission, and

the number of terminals that are performing VoIP (Voice over InternetProtocol),

each of which is unicast related information.

In the present invention, one or more of an outage of a predeterminedindex that is defined in advance, a coverage, a transmission rate, areceived SIR (Signal-to-Interference Ratio), and a received SINR(Signal-to-Interference and Noise Power Ratio) is used as a requirementcondition for an MBSFN quality.

For setting a target value of an MBSFN outage, there are two methods; inone method, the MBSFN transmission rate is kept (almost) constant and,in another method, the transmission rate is not considered (thecondition for keeping the transmission rate constant is not set). For anMBSFN coverage, there are also two methods; that is, in one method theMBSFN coverage is kept (almost) constant and, in another method, thecondition for keeping the MBSFN coverage constant is not set.

In the present invention, as the transmission parameter that configuresthe communication control information in an MBSFN area, at least one of

a modulation scheme,

a coding rate,

an allocation, an allocation rate, or an allocation amount of a radioresource used for MBSFN transmission,

a transmission power or a maximum of the transmission power,

a reference signal composed of a known sequence, and

a scrambling code

may be output. More specifically,

at least one of

a modulation scheme,

a coding rate,

the number of MBSFN subframes,

an MBSFN subframe position

an MBSFN frame position

an MBSFN frame period

a transmission power or a maximum of the transmission power of acommunication that is performed by a radio station, which does notcontribute to MBSFN transmission, and that is performed at the same timeMBSFN transmission is performed,

a frequency usage rate of a communication that is performed by a radiostation, which does not contribute to MBSFN transmission, and that isperformed at the same time MBSFN transmission is performed,

a frequency resource of a communication that is performed by a radiostation, which does not contribute to MBSFN transmission, and that isperformed at the same time MBSFN transmission is performed,

a reference signal, and

a scrambling code

is output. A radio station that does not contribute to MBSFN in an MBSFNarea performs one of unicast transmission and multicast transmission.

In the present invention, MBSFN transmission and unicast transmissionare multiplexed in a time domain on a per frame basis, the frame beingcomposed of N subframes (N is a predetermined positive integer) and anumber of subframes is used as an allocation amount of a radio resourceused for the MBSFN transmission. It is of course possible to apply thepresent invention to a method in which the transmission is multiplexedon a basis of multiple frames.

In the present invention, MBSFN transmission and unicast transmissionmay be multiplexed in a time domain on a per frame basis, the framebeing composed of N subframes (N is a predetermined positive integer)and,

in allocating a radio resource used for the MBSFN transmission, at leastone of

a subframe number used for MBSFN transmission,

a start subframe number and the number of subframes to be used,

a frame number used for MBSFN transmission or information indicating aframe number, and

a frame period at which MBSFN transmission is performed may be used.

In the present invention, MBSFN transmission and unicast transmissionmay be multiplexed in the frequency domain and,

as an allocation amount of a radio resource used for the MBSFNtransmission, a total of continuous or discontinuous frequency bands(resources) may be used.

In the present invention, MBSFN transmission and unicast transmissionmay be multiplexed in the frequency domain and,

as an allocation of a radio resource used for the MBSFN transmission,positions of continuous or discontinuous frequency bands (resources) maybe used.

In the present invention, as transmission parameters for the unicasttransmission that is performed at the same time MBSFN transmission isperformed,

at least one of

a transmission power or a maximum of the transmission power,

a frequency usage rate, and

a frequency band (resource),

may be used.

In the present invention, the transmission parameter for the MBSFN areais controlled so that a point-to-point (PTP) total system throughput ofunicast transmission in the MBSFN applicable area is increased ormaximized while satisfying the MBSFN requirement condition. That is, thecriterion for determining the transmission parameters for the MBSFN areais that the PTP system throughput of the MBSFN area is increased ormaximized while satisfying the MBSFN quality requirement.

Next, the present invention will be described below in detail withreference to the drawings. In the description below, an example based on3GPP LTE (Long Term Evolution), one of the objects to which the presentinvention is applied, is used and, in the example, the MBSFN-relatedinformation is used as the communication status information and at leastthe transmission parameters are used as the communication controlinformation. In 3GPP LTE, MBSFN and unicast are time-divisionmultiplexed but not frequency-multiplexed. And, the information on theradio resources by which MBSFN (i.e. transmission parameter specified ascommunication control information) is performed is notified from a basestation to a terminal as MSAP (MCH Subframe Allocation Pattern). MSAPincludes micro-level information on a subframe basis and the macro-levelinformation on a per frame basis. Therefore, the information on thenumber of MBSFN subframes and their positions and the information on thepositions and the period of an MBSFN frame in the present embodiment areincluded in MSAP.

In LTE, the information that is controlled by the present invention isdefined as follows.

For example,

information on the subframes that may be used (reserved) for MBSFN isdefined as “mbsfn-Subframe Configuration” (configuration ofmbsfn-subframe),

information on MBSFN frames (frame number, frame period, etc.) isdefined as “radio Frame Allocation” (allocation of radio frame), and

information on the number of MBSFN subframes is defined as “subframeAllocation” (sub-frame allocation).

One MBSFN area is composed, for example, of:

only the MBSFN service cells that perform MBSFN transmission or

MBSFN service cells that perform MBSFN transmission and reserved cellsthat perform unicast or single-cell/multicast transmission.

In the claims and the specification of the present application, a radiostation (base station) that does not contributes to MBSFN transmissionmeans a radio station (base station) that does not communicate via MBSFNregardless of whether or not the radio station (base station) supportthe MBSFN function. Therefore, in the embodiment described below, a basestation that serves a reserved cell but does not contribute to MBSFNtransmission may or may not have the MBSFN function in practice.

At the time MBSFN subframes are transmitted, a base station (eNodeB:called “eNB”) in a reserved cell reduces the transmission power andperforms unicast transmission, does not perform unicast transmission atall, or performs single-cell/multicast transmission for a terminal (UserEquipment: called “UE”) to reduce interference to the MBSFN servicecells for improving the MBSFN quality. Although not limited thereto, itis assumed in the embodiments described below that the cell type(whether the cell is an MBSFN service cell or a reserved cell) wasalready notified from MCE to eNB, for example, when MBSFN wasinitialized. The cell type is notified again to eNB when the cell typeis changed or at a periodic interval. The cell type may be notifiedeither with the transmission parameters, which will be described later,or separately. In the description of the embodiment below, thedescription of the cell type notification processing is omitted.

FIG. 1 is a diagram showing components on a radio communication networkside that performs MBSFN transmission in the present invention. In FIG.1,

eBMSC (enhanced Broadcast Multicast Service Centre) 101

(A) notifies an MCE (Multi-cell/multicast Coordination Entity) 103 aboutMBMS control information, such as a MBMS session control signal or MBMStraffic information, via an E-MBMS GW (gateway) 102, and

(B) notifies a base station (eNB) 104 about MBMS data that will betransmitted to a terminal (UE) via MBSFN.

The MCE 103 allocates time and frequency radio resources to a basestation (eNB), located in an MBSFN area, in which MBMS data istransmitted to multiple cells using MBSFN, and at the same time,determines the detail of the radio configuration such as a modulationand coding scheme. The MCE 103 performs an MBMS session controlsignaling processing but not a UE-MCE signaling processing. The MCE 103is a logical entity. The MCE 103 may not be an independent apparatus andbe a part of other network elements.

More specifically, the MCE 103

(A) generates MBSFN configuration information based on the MBMS controlinformation, notified by the eBMSC 101 via the E-MBMS GW 102, and theMBSFN related information notified by the eNB 104, and notifies theeBMSC 101 about the generated information via the E-MBMS GW 102. The MCE103 also

(B) generates the MBSFN control information and notifies the eNB 104about the generated information.

The MBSFN related information that the MCE 103 is notified by the eNB104 includes the following.

(1) Information on the components of the MBSFN area such as:

Number of cells served by base stations that perform MBSFN;

Size (radius) of a cell served by a base station that performs MBSFN;

Number of cells served by base stations that perform unicast orsingle-cell/multicast; and

Size (radius) of a cell served by a base station that performs unicastor single-cell/multicast;

(2) Multicast related information on MBSFN area such as:

Number of UEs that are receiving MBSFN or information that makes itpossible to estimate the number of the UEs;

Number of UEs that want to receive MBSFN or information that makes itpossible to estimate the number of the UEs;

Quality (error rate) of MBSFN in execution or information that makes itpossible to estimate the quality; and

Ratio of the number of UEs that are receiving MBSFN to the number of UEsthat are receiving unicast;

(3) Unicast related information such as:

PTP traffic volume of unicast;

Number of UEs that are receiving unicast;

Number of UEs in an active state that may receive unicast; and

Number of UEs that are performing VoIP (Voice over Internet Protocol)service.

Note that (1)-(3) described above need not be notified always at thesame time. For example, the information such as (1), which, oncenotified, remains unchanged for a long time or semi-permanently, isrequired to be notified again only when the information is changed.

The MBSFN configuration information generated by the MCE 103 includesthe following:

-   -   Which eNB performs MBSFN; and    -   In which order the services are offered if there are multiple        MBSFN service candidates.

The MBSFN control information notified from the MCE 103 to the eNB 104includes the following:

-   -   MCS of MBSFN;    -   Number of MBSFN subframes;    -   Positions of MBSFN subframes;    -   Positions of MBSFN frames;    -   Period of MBSFN frame;    -   Reference signal of MBSFN;    -   Scrambling code of MBSFN;    -   Transmission power or maximum of transmission power in a        reserved cell;    -   Frequency usage rate in a reserved cell; and    -   Frequency band (resource) in a reserved cell.

The E-MBMS GW (gateway) 102 transmits/reports an MBMS packet with theSYNC protocol (protocol for synchronizing data used for generating radioframes) to the eNB that performs MBSFN transmission. The MBMS GW 102hosts the PDCP (Packet Data Convergence Protocol) layer in the userplane and transfers MBMS user data to the eNB via IP multicast. The MBMSGW 102 performs MBMS session control signaling (session start/stop) foran E-UTRAN (Evolved Universal Terrestrial Radio Access Network). Notethat the E-MBMS GW 102, which is a logical entity, may be a part ofanother network element.

The M3 interface (between MCE and MBMS GW) is a control plane interfacebetween E-UTRAN and EPC (Evolved Packet Core) and, on this interface,MBMS session control signaling is performed as an application on the EPSbearer level (radio configuration data is not transmitted). MBMS sessioncontrol signaling includes signaling for starting/stopping an MBMSsession. SCTP (Stream Control Transmission Protocol) is used as thesignaling transfer protocol (PTP signaling).

The M2 interface (between MCE and eNB) is a control plane interface inE-UTRAN and, on this interface, the radio configuration data on amulti-cell transmission mode eNB and a single-cell transmission mode eNBthat configures a reserved cell (if any) in an MBSFN area, and thesession control signaling are transmitted as an application. SCTP(Stream Control Transmission Protocol) is used as the signaling transferprotocol (PTP signaling).

The M1 interface (between MBMS GW and eNB) is a user plane interface,and no control plane application is defined. IP multicast is used forthe point-to-point transmission of user packets in the single-celltransmission and multi-cell transmission.

In the multi-cell transmission, the MCE 103 collects multicast relatedinformation and/or unicast related information from all eNBs, or a partof multiple eNBs, in the same MBSFN area.

The multicast related information includes the following:

-   -   Number of UEs that receive/request (want to receive) MBMS/MBSFN        for each content; and    -   MBMS/MBSFN error rate.

The unicast related information includes, for example, the following:

-   -   Number of UEs in active state, that is, in RRC_CONENCTED state        (state in which a radio link is established);    -   Number of UEs that are performing VoIP (Voice over IP); and    -   PTP traffic volume.

The multicast and unicast related information includes a ratio of thenumber of multicast-receiving UEs to the number of unicast-receiving UEs(or vice-versa).

It is also possible that the MCE 103 does not collect the ratio of thenumber of multicast-receiving UEs to the number of unicast-receiving UEsbut that the MCE 103 collects the number of multicast-receiving UEs andthe number of unicast-receiving UEs and calculates the ratio.

As described above, the MCE determines the transmission parameter forMBSFN transmission or unicast transmission in an MBSFN area. The MBSFNtransmission parameter includes, for example, as follows:

-   -   Number of MBSFN subframes;    -   MSAP (Multicast channel Subframe Allocation Pattern) indicating        micro/macro level allocation;    -   MCS; and    -   Transmission power or the maximum of transmission power of MBSFN        transmission.

The unicast transmission parameter includes, for example, as follows:

-   -   Transmission power or the maximum of transmission power; and    -   Usable frequency band (resource)        in a MBSFN subframe in a reserved cell in an MBSFN area.

FIG. 2 is a sequence diagram showing a control procedure used in theembodiment shown in FIG. 1. Base stations eNB1-eNBn, each serving anMBSFN service cell, collect (measurement) information, defined inspecifications in advance, or information requested by the MCE, andreports the measurement result to the MCE (“eNB Measurement Report” inFIG. 2).

Based on the measurement report (eNB Measurement Report) received fromthe base stations eNB1-eNBn, the MCE checks if the MBSFN (or MBSFN andunicast) transmission parameter in the MBSFN area needs to be reset(“Reconfiguration decision” in FIG. 2: decide to reset the parameter).

If it is determined by the MCE that the MBSFN transmission parameterneeds to be reset, the MCE actually resets the MBSFN transmissionparameter (“MBSFN setting update” in FIG. 2: update the MBSFN setting)and transmits a reconfiguration request to the eBMSC via the E-MBMS GW(“Reconfiguration Request” in FIG. 2: request for reset).

In response to the request for reconfiguration (ReconfigurationRequest), the eBMSC reconfigures the transmission parameter using thesame procedure as the MBSFN transmission parameter configurationprocedure used when MBSFN is started (“MBSFN reconfiguration” in FIG.2). Note that the parameter may be reconfigured not only by an absolutevalue but also by a relative value such as a difference or a rate.

As shown in FIG. 2, the information included in the eNB measurementreport includes, for example, as follows.

-   -   Volume of PTP traffic in unicast transmission;    -   Number of active UEs performing unicast transmission;    -   Number of VoIP UEs;    -   Number of UEs receiving MBSFN;    -   Number of UEs requesting MBSFN; and    -   MBSFN quality (error rate, etc.) (Error rate of MBSFN service).

Of course, the information is not limited to those given above.

FIG. 3 is another diagram showing components on the radio communicationnetwork side that performs MBSFN transmission. The basic configurationis the same as that in FIG. 1, except that the eNBs are divided into twotypes: an eNB 105 that serves a reserved cell and an eNB 106 that servesan MBSFN service cell. FIG. 4 is a sequence diagram showing the controlprocedure used in the configuration shown in FIG. 3.

Base stations eNB1-eNBm each serving an MBSFN service cell and basestations eNBm+1-eNBn each serving a reserved cell collect (measurement)the information defined by specifications in advance or the informationspecified by MCE, and report the result to the MCE (“eNB MeasurementReport” in FIG. 4).

Based on the eNB measurement report (eNB Measurement Report), the MCEchecks if the MBSFN transmission parameter needs to be reset(“Reconfiguration decision” in FIG. 4).

If it is determined by the MCE that the MBSFN area transmissionparameter must be reset, the MCE actually resets the MBSFN areatransmission parameters and transmits a reconfiguration request to theeBMSC via the E-MBMS GW (“Reconfiguration Request” in FIG. 4 n).

In response to the reconfiguration request (Reconfiguration Request),the eBMSC resets the parameters using the same procedure as the MBSFNtransmission parameter configuration procedure used when MBSFN isstarted.

As shown in FIG. 4, an example of the information included in the eNBmeasurement report notified by eNB1-eNBm, each serving an MBSFN servicecell, is as follows:

-   -   Volume of PTP traffic in unicast transmission;    -   Number of active UEs performing unicast transmission;    -   Number of VoIP UEs;    -   Number of UEs receiving MBSFN (or information that makes it        possible to estimate the number of the UEs on the MCE side); and    -   Number of UEs requesting MBSFN (or information that makes it        possible to estimate the number of the UEs on the MCE side)        error rate, etc.) (Error rate of MBSFN service).

On the other hand, the eNB Measurement Report information notified byeNBm+1-eNBn each serving a reserved cell includes, for example, asfollows:

-   -   Volume of PTP traffic in unicast transmission;    -   Number of active UEs performing unicast transmission; and    -   Number of VoIP UEs.        Of course, the information is not limited to those given above.

FIG. 5 is a diagram showing the configuration in which the MCE is one ofthe functional blocks of an eNB. As described above, the MCE, which is alogical entity, may be a part of other network equipment instead ofbeing provided as a standalone equipment. In this example, the MCE isinstalled in the eNBs, that is, an MCE 107 is included in eNBs 108 and109, one for each. In the configuration shown in FIG. 5, the function toexchange and control information between the MCEs installed in the eNBsis required in the E-MBMS GW. In FIG. 5, the eNB 108 is a base stationthat serves a reserved cell, and the eNB 109 is a base station thatserves an MBSFN service cell.

The operation will be described, based on the configuration of FIG. 3,assuming the 3GPP LTE technology. FIG. 6 and FIGS. 7A-7B are diagramsshowing the basic concept of transmission parameter control in an MBSFNarea in the present embodiment.

In the description below, it is assumed that the MBSFN area is composedonly of MBSFN service cells (no reserved cell), and the transmissionparameter that is controlled is as follows:

-   -   Number of MBSFN subframes; and    -   MBSFN MCS.

First, the PTP traffic volume is measured for each cell in the MBSFNarea and, as shown in FIGS. 7A and 7B, the following is calculated as arepresentative value:

-   -   Average value; or    -   Maximum value (or minimum value).

Based on this representative value of the PTP traffic volume, a check ismade if the PTP traffic volume is increased as compared with that atMBSFN transmission start time (or at the most recent control time) and,if so, the following processing is performed as shown in FIG. 6.

Alt. 1) Decrease the number of MBSFN subframes and use a higher MBSFNMCS, or

Alt. 2) Decrease the number of MBSFN subframes but do not change MBSFNMCS.

The purpose of Alt. 1 is to keep the MBSFN service rate constant. Inthis case, the PTP resource (PTP capacity) is increased but the MBSFNcoverage is decreased.

On the other hand, the purpose of Alt. 2 is to keep the MBSFN coverageconstant. The PTP resource (PTP capacity) is increased but the MBSFNservice rate is decreased.

As described above, there is a tradeoff between the MBSFN service rate(service quality) and the MBSFN coverage, and which to select is decidedaccording to which should have higher priority, MBSFN service rate orMBSFN coverage.

Conversely, if the PTP traffic volume is decreased as compared with thatat MBSFN transmission start time (or at the most recent control time),the following processing is performed.

Alt. 3) Increase the number of MBSFN subframes and use a lower MBSFNMCS, or

Alt. 4) Increase the number of MBSFN subframes but do not change MBSFNMCS.

The purpose of Alt. 3 is to increase an MBSFN coverage while keeping theMBSFN service rate constant.

The purpose of Alt. 4 is to increase an MBSFN service rate while keepingthe MBSFN coverage constant.

As described above, which to select, Alt. 3 or Alt. 4, is decidedaccording to which should have higher priority, MBSFN service rate orMBSFN coverage.

Note that, as a combination of an increase or decrease in the PTPtraffic volume as compared with that at MBSFN transmission start time(or at the most recent control time), it is possible to combine any oneof Alt. 1 and Alt 2 in FIG. 6 with any one of Alt. 3 and Alt. 4.

FIG. 8 to FIG. 10E are diagrams showing the control based on the conceptof this embodiment described with reference to FIG. 6. Assume that theMBSFN area is composed only of MBSFN service cells.

Assuming that there is an MBSFN area composed of multiple MBSFN servicecells and that unicast cells are adjacent to the MBSFN area, as shown inFIG. 8.

In practice, the cells are a group of two-dimensionally arranged cellssuch as those shown in FIG. 24. FIG. 8 shows a part of the group (shownone-dimensionally). In the description below, it is assumed that theMBSFN area is fixed and composed of the following base stations.

eNBA1-A5 are base stations each of which serves an MBSFN service cellthat belongs to the MBSFN area and performs MBSFN in MBSFN subframes;and

eNBC1 and eNBC2 are base stations each of which does not belong to theMBSFN area and performs only unicast.

In this case, eNBA1-A5 exchange information with the MCE and receiveMBMS data from the eBMSC via E-MBMS GW and transmit the received data tothe terminals (UE).

On the other hand, the operation of eNBC1 and eNBC2 is independent ofthe base stations in the MBSFN area where the present invention is usedand, therefore, the description is omitted here.

As shown in FIGS. 9A-9E, it has been assumed that an increase in the PTPtraffic volume is detected at time t=t0. FIGS. 9B and 9C show the MBSFNservice rate (MBSFN service rate) and the reception quality (Rx quality)in the cells shown in FIG. 8 at time t0 and t1.

In this case, Alt. 1 in FIG. 6 is used to decrease the number of MBSFNsubframes and increase the MBSFN MCS so that the MBSFN service rate iskept constant.

This indicates that, at time t=t1, the MBSFN service rate is keptunchanged but the MBSFN reception quality is decreased (see the downarrow in FIG. 9C). Note that the PTP resource is increased.

On the other hand, Alt. 2 in FIG. 6 is used in FIGS. 10A-10E to decreaseonly the number of MBSFN subframes for keeping the reception qualityconstant so that the MBSFN coverage is kept unchanged. FIGS. 10B and 10Cshow the MBSFN service rate (MBSFN service rate) and the receptionquality (Rx quality) of the cells in FIG. 8 at time t=t0 and t1.

This indicates that, at time t=t1, the MBSFN reception quality is keptunchanged but the MBSFN service rate is decreased (see the down arrowindicating the MBSFN service rate in FIG. 9C).

FIG. 11 and FIGS. 12A-12I are diagrams showing the control based on theconcept of the present embodiment described with reference to FIG. 6. Inthose figures, it is assumed that the MBSFN area is composed of MBSFNservice cells and reserved cells. FIG. 12B to FIG. 12E show thereception quality (Rx quality) of the cells shown in FIG. 11 at timest=t0-t3. FIG. 12F-FIG. 12I show the control performed by the MCE attimes t=t0-t3 in FIG. 12B-FIG. 12E.

As shown in FIG. 11, it is assumed that there is an MBSFN area composedof MBSFN service cells and reserved cells and that there are neighboringunicast cells.

Also it is assumed that the MBSFN area is fixed as follows:

eNBA1-A3 and eNBB1 and B2 are base stations that belong to the MBSFNarea; and

eNBC1 and C2 are base stations that do not belong to the MBSFN area andthat perform only unicast transmission.

Among base stations that belong to the MBSFN, eNBA1-A3 are base stationthat serves the MBSFN service cells, and

eNBB1 and B2 are base stations that serve reserved cells.

In this case, eNBA1-A3 and eNBB1 and B2 exchange information with theMCE, and eNBA1-A3 receive MBMS data from the E-MBMS GW and transmits thereceived data to terminals (UE) not shown.

On the other hand, the operation of the base stations eNBC1 and eNBC2,which do not belong to the MBSFN area and which perform only unicasttransmission, is independent of the base stations in the MBSFN areawhere the present invention is used and, therefore, the description isomitted here.

As the transmission parameter control method in the MBSFN area, Alt. 1in FIG. 6 is used in which the MBSFN service rate is kept constant.

First, in FIG. 12B, it is assumed that an increase in the PTP trafficvolume in the reserved cells is detected at time t=t0 (step 0 in FIG.12F).

Therefore, the number of MBSFN subframes is decreased and a higher MBSFNMCS is used to keep the MBSFN rate constant (step 1).

Then, the MBSFN reception quality (Rx quality) is deteriorated at timet=t1 as shown in FIG. 12C (step 2 in FIG. 12G).

To address this problem, the transmission power in the reserved cells isdecreased at time t=t2 (FIG. 12D) to try to improve the MBSFN receptionquality (step 3 in FIG. 12H).

As a result, at time t=t3 (FIG. 12E), the reserved cell receptionquality is deteriorated but, instead, the MBSFN reception quality isimproved (step 4 in FIG. 12I).

As described above, arranging the reserved cells on the periphery of theMBSFN service cells and decreasing the transmission power in thereserved cells could prevent the MBSFN reception quality from beingsignificantly deteriorated while keeping the MBSFN service rate.

With the configuration, shown in FIG. 11, as the basic configuration,embodiments will be described below in detail. A method is used in whichan outage target value is satisfied while keeping the MBSFN service rate(almost) constant in order to satisfy the MBSFN quality requirement.

First Exemplary Embodiment

In a first exemplary embodiment of the present invention, based on

-   -   PTP traffic volume (load) of reserved cells and    -   Target value of MBSFN outage probability, the following are set        so that the total system throughput of the MBSFN area is        maximized:    -   Number of MBSFN subframes;    -   MBSFN MCS; and    -   Transmission power or maximum of transmission power for MBSFN        subframes in a reserved cell.

An example of an MBSFN outage probability is what percent of UEs dosatisfy a required error rate (for example, 10-percent PER (Packet ErrorRate) or BLER (Block Error Rate)). An example of the target is that theoutage probability is required to be 5%, that is, UEs satisfying therequired error rate is required to be 95% or higher.

In the present embodiment, MBSFN subframes are assumed to be included ineach frame.

To implement the present embodiment, there is provided in advance atable showing the relation among the following items:

MBSFN outage probability (%);

MBSFN MCS; and

Transmission power or the maximum transmission power in a reserved cell

The values shown in this table largely depend on the number of MBSFNsubframes or on a cell radius of an MBSFN area. Therefore, an evaluationresult obtained in advance by computer simulation or by statistical dataobtained on actual apparatuses is used.

As shown in expression (1) shown below, a sum of the system throughputof the MBSFN service cells and that of the reserved cells is calculatedto calculate a system throughput of the MBSFN area.

$\begin{matrix}{{System\_ throughput} = {{\sum\limits^{S}\; {{{Min}\left( {{generated\_ traffic},{acceptable\_ traffic}} \right)}\mspace{14mu} \ldots \mspace{14mu} {MBSFN}\mspace{14mu} {Service}\mspace{14mu} {cell}}} + {\sum\limits^{R}\; {{{Min}\left( {{generated\_ traffic},{acceptable\_ traffic}} \right)}\mspace{14mu} \ldots \mspace{14mu} {Reserved}\mspace{14mu} {cell}}}}} & (1)\end{matrix}$

where

S is the number of MBSFN service cells in the MBSFN area of interest and

R is the number of reserved cells in the MBSFN area of interest.

“Acceptable traffic” is a function of the number of MBSFN subframes,MCS, and the transmission power or the maximum of the transmission powerin the reserved cells. If MBSFN subframes are not always included inevery frame, the MBSFN frame period is also one of the variables.

The number of MBSFN subframes, MCS, and the transmission power or themaximum of the transmission power in the reserved cells, which maximizethe total system throughput of this MBSFN area, are set.

FIG. 13 is a diagram showing the configuration of the base stations(eNB) in the first exemplary embodiment. In this figure, an eNB 201 isassumed to perform MBSFN transmission. Referring to FIG. 13, this basestation (eNB) 201 comprises an MBSFN control unit 202, an MBSFN signaltransmission unit 203, a unicast signal control unit 204, a unicastsignal transmission unit 205, a unicast signal reception unit 206, aunicast signal demodulation unit 207, and an MBSFN related informationgeneration unit 208.

The MBSFN control unit 202 receives MBSFN control information from theMCE, and outputs MBSFN transmission control information to the MBSFNsignal transmission unit 203 and MBSFN subframe information to theunicast signal control unit 204 respectively.

The MBSFN signal transmission unit 203 generates an MBSFN signal basedon the MBSFN data and the MBSFN transmission control information, andtransmits the generated MBSFN signal to a terminal (UE) not shown.

The unicast signal control unit 204 outputs a unicast transmissioncontrol information to the unicast signal transmission unit 205, andunicast transmission information to the MBSFN related informationgeneration unit 208, based on DL (Downlink) unicast information andMBSFN subframe information.

The unicast signal transmission unit 205 generates a DL unicast signalbased on the DL unicast information and unicast transmission controlinformation, and transmits the generated DL unicast signal to a UE.

On the other hand, the unicast signal reception unit 206 receives a UL(Uplink) unicast signal and outputs the received UL unicast signal tothe unicast signal demodulation unit 207.

The unicast signal demodulation unit 207 demodulates the receivedunicast signal, transmits UL unicast information to the MME/S-GW(Mobility Management Entity/Serving Gateway), and outputs MBSFN feedbackinformation to the MBSFN related information generation unit 208.

The MBSFN related information generation unit 208 generates MBSFNrelated information based on the unicast transmission information andthe MBSFN feedback information, and transmits the generated MBSFNrelated information to the MCE. The function/processing of the MBSFNcontrol unit 202, MBSFN signal transmission unit 203, unicast signalcontrol unit 204, unicast signal transmission unit 205, unicast signalreception unit 206, unicast signal demodulation unit 207, and MBSFNrelated information generation unit 208 in this base station may beimplemented by a programs executed on a computer configuring the basestation.

FIGS. 14A and 14B are flowcharts showing processing performed in thebase station shown in FIG. 13. FIG. 14A shows the flow of transmissionfrom the base station to a UE.

The unicast signal control unit 204 of the base station is assumed toreceive the DL unicast information from the MME/S-GW.

First, the MBSFN control unit 202 of the base station (eNB) checks ifthe MBSFN control information has been received from the MCE, that is,if the base station belongs to an MBSFN area (S102). If the base stationdoes not belong to an MBSFN area (No in S102), the usual unicasttransmission is assumed and the unicast signal transmission unit 205performs only the unicast transmission (S107).

If the MBSFN control information is received from the MCE (Yes in S102),the MBSFN control unit 202 checks if the type of the cell that the MBSFNcontrol unit 202 serves is an MBSFN service cell or a reserved cell(S103).

If the MBSFN control unit 202 recognizes that the cell is a reservedcell as a result of the cell type checking in step S103 (No in S104),the base station (eNB) performs only the unicast transmission throughthe unicast signal transmission unit 205 (S107).

If the MBSFN control unit 202, recognizes that the cell is an MBSFNservice cell as a result of the cell type checking in step S103 (Yes inS104) and if the subframe is an MBSFN subframe (Yes in S105), the MBSFNsignal transmission unit 203 transmits the MBSFN signal (S106). Fornon-MBSFN subframes, the unicast signal transmission unit 205 performsthe unicast transmission (S107).

On the other hand, FIG. 14B shows a flow of transmission from a basestation to the MCE.

The unicast signal control unit 204 of the base station (eNB) receivesthe DL unicast information from the MME/S-GW (S110).

The MBSFN control unit 202 of the base station (eNB) checks if the basestation (eNB) belongs to an MBSFN area (S111). If the base station (eNB)does not belong to an MBSFN area (No in S111), the unicast signaltransmission unit 205 performs only the usual unicast transmission.

If the base station (eNB) belongs to an MBSFN area, the MBSFN controlunit 202 of the base station (eNB) checks if the time matches the timingfor notifying the MCE about the MBSFN information (time t=n*TReport),that is, checks if a control time has arrived (S112).

If the control time has arrived (Yes in S112), the MBSFN relatedinformation generation unit 208 measures the PTP traffic volume for eachcell (S113), generates MBSFN related information that includes a PTPtraffic volume, and transmits the generated MBSFN related information tothe MCE (S114).

The MCE determines a MBSFN area transmission parameter based on theMBSFN related information.

FIG. 15 is a block diagram showing the configuration of the MCE in thefirst exemplary embodiment. It is assumed that an MCE 209 is connectedto one E-MBMS GW and multiple eNBs. Referring to FIG. 15, the MCE 209comprises a system throughput estimation value calculation unit 210 anda transmission mode control unit 211.

The system throughput estimation value calculation unit 210 calculates asystem throughput estimation value, as shown in expression (1) givenabove, based on the MBMS control information received from the E-MBMS GWand the MBSFN related information received from the multiple eNBs, andoutputs the system throughput and its parameters to the transmissionmode control unit 211 as the transmission parameter set information.

The transmission mode control unit 211 determines the MBSFN and unicasttransmission modes, based on the table (not shown) indicating therelation among:

Transmission parameter set information;

MBSFN outage probability (%);

MBSFN MCS; and

Transmission power or the maximum of the transmission power in thereserved cells.

Then, the transmission mode control unit 211 sends the MBMSconfiguration information to the E-MBMS GW, and the MBSFN controlinformation to the eNBs, respectively. Note that the function/processingof the system throughput estimation value calculation unit 210 and thetransmission mode control unit 211 may be implemented by the programexecuted on the computer configuring the MCE 209.

FIG. 16 is a flowchart showing the processing of the MCE shown in FIG.15.

The system throughput estimation value calculation unit 210 of the MCEnotifies the base stations about a default setting of the MBSFN areatransmission parameter and then waits for the MBSFN related information,which includes a PTP traffic volume, to be reported from the basestations.

If a control time, that is, an update time of the MBSFN areatransmission parameter, has arrived (Yes in S204) before the MBSFNrelated information is reported, the transmission mode control unit 211of the MCE notifies the base stations about the default setting (or themost recent setting) that has not been updated (S205).

If the MBSFN related information is reported from the base station (Yesin S201), the system throughput estimation value calculation unit 210 ofthe MCE calculates a time average of PTP traffic volume by performing asimple moving averaging or a weighted moving averaging, based on the PTPtraffic volume information included in the MBSFN related information,and a previously reported PTP traffic volume (S202).

The system throughput estimation value calculation unit 210 of the MCEcalculates a system throughput, based on the time average of the PTPtraffic volume, with the MBSFN area transmission parameters as avariable (S203), and determines a combination of transmission parametersthat maximize the total of the system throughputs of the MBSFN area.

The transmission mode control unit 211 of the MCE checks if the controltime has arrived (S204) and, if the control time has arrived (Yes inS204), notifies the base station about the determined transmissionparameter of the MBSFN area (S205).

The following describes the procedure for determining the MBSFN andunicast transmission parameters in the first exemplary embodiment.

In the description below, it is assumed that eNBA1-A3 and eNBB1-B2belong to the same MBSFN area and exchange information with the MCE andthat eNBA1-A3 perform both unicast transmission and MBSFN transmissionand eNBB1-B2 perform only unicast transmission.

The MCE has a table, such as the one shown in FIG. 17, that is createdby calculating the relation among the MBSFN outage probability (%), MCS,and transmission power, or maximum of transmission power, in thereserved cells. This table is stored in a memory, not shown, (forexample, rewritable, non-volatile memory) in the system throughputestimation value calculation unit 210 of the MCE in FIG. 15.

Each eNB in the MBSFN area measures the PTP traffic volume for each cellat a periodic interval of TReport (=T) and notifies the MCE about themeasured volume.

The system throughput estimation value calculation unit 210 of the MCEcalculates the average of each of the following:

reported values of the PTP traffic volume from the eNBs each serving anMBSFN service cell; and

reported values of the PTP traffic volume from the eNBs each serving areserved service cell.

After that, based on the calculated averages of the PTP traffic volumes,the transmission mode control unit 211 of the MCE determines thefollowing at a periodic interval of Tctrl (for example,Tctrl=5*TReport=5T).

Number of MBSFN subframes, and MCS of MBSFN; and

Transmission power or the maximum transmission power used for MBSFNsubframes in a reserved cell.

If the control period (Tctrl) of the MCE is longer than the period ofreport (TReport) from an eNB as in the present embodiment, one of thefollowing two methods is used:

Simple moving average in which the report values received from the eNBsat each time are simply time-averaged; and

Weighted moving average in which the report values received from theeNBs at each time are weighted.

In the description below, these two methods are simply called as a timeaverage with no distinction between them.

At a specified point of time t, the system throughput estimation valuecalculation unit 210 of the MCE first creates a table, such as the oneshown in FIG. 18, indicating the relation among

-   -   MBSFN outage probability (%);    -   MCS and number of MBSFN subframes; and    -   Transmission power or the maximum transmission power used in a        reserved cell,

based on the MBMS transmission rate (or service type information thatmakes it possible to estimate the MBMS transmission rate) included inthe MBMS control information notified by the E-MBMS GW and on the tableshown in FIG. 17.

Now, it is assumed that the target value of the MBSFN outage probabilityis 10%. In this case, in FIG. 18, the candidates for a combination ofthe transmission power or the maximum of the transmission power for theMBSFN subframes in a reserved cell, MBSFN MCS, and the number of MBSFNsubframes, which satisfy the outage probability=10%, are the followingthree.

([Reserved cell power],[MBSFN MCS]/[# of subframes])=(50%,⅛),(10%,2/7),(0%,10/1)

Based on the time-average value of the PTP traffic for the periods 5T,t=T0 to t=T4, because the control period of the MCE is 5T, the systemthroughput is calculated for each of the combinations of the above threeusing expression (1) and the combination is selected that achieves themaximum throughput.

Now, it is assumed that the system throughput of each of thecombinations described above is 180 Mbps, 220 Mbps, and 340 Mbps,respectively. In this case, the transmission mode control unit 211 ofthe MCE determines the transmission parameters as follows:

Transmission power in MBSFN subframes in a reserved cell is 0% of themaximum transmission power (that is, in a reserved cell, the MBSFNsubframes are not used for unicast transmission),

MBSFN MCS is 10, and

Number of MBSFN subframes is 1.

The transmission mode control unit 211 of the MCE notifies each eNBabout the determined transmission parameters, and in accordance withthis notification, the eNB performs MBSFN or unicast transmission.

It is assumed that the result of observation of a PTP traffic volume fora given period is as shown in FIG. 19A. In this case, the transmissionparameters of the MBSFN and unicast in a reserved cell, which aredetermined according to the method described above, are as shown in FIG.19B.

FIG. 19A indicates that, because a time average of the PTP trafficvolume at a time t=T10 is slightly lower than that at a time t=T5, asmaller MBSFN MCS is used instead of increasing the number of MBSFNsubframes, as shown in FIG. 19B, to increase the transmission power inthe reserved cells.

On the other hand, because the PTP traffic volume is increased suddenlyat a time t=T15, a larger MBSFN MCS is used instead of significantlydecreasing the number of MBSFN subframes and, as a result, thetransmission power in the reserved cells is set very low.

In this way, the adaptive control described above is able to support atransmission mode that is optimal for MBSFN and unicast transmission inthe MBSFN area in accordance with an ever-changing PTP traffic volume.

In the present embodiment, though the periodic interval Treport at whichan eNB notifies the MCE about the PTP traffic volume and the periodicinterval Tctrl at which the MCE notifies an eNB about the transmissionparameters, are set individually, those two may be set at the sameinterval.

A trigger-based method may also be used in which the notification ismade when at least one or both satisfy the pre-defined condition.

In the embodiment described above, the average of the PTP trafficvolumes reported by the eNBs belonging to MBSFN service cells orreserved cells is used. Instead of the average,

-   -   Representative value that is the largest or smallest at each        time, or    -   Average of the center N values of the values reported by M eNBs        (N<M)        may also be used.

Second Exemplary Embodiment

In a second exemplary embodiment of the present invention, based on

-   -   PTP traffic volume (load) of reserved cells; and    -   Target value of MBSFN outage probability, the following are set        so that the total system throughput of an MBSFN area is        maximized:    -   Number of MBSFN subframes;    -   MBSFN MCS; and    -   Transmission power or maximum of transmission power for MBSFN        subframes in a reserved cell.

The difference between the present embodiment and the first exemplaryembodiment is that, in the present embodiment, the relation between thePTP traffic volume and the system throughput is derived by expression(1) in advance to create a table that is stored in the memory.

Doing so reduces the amount of calculation in the MCE.

FIG. 20 is a block diagram showing the configuration of the MCE in thesecond exemplary embodiment. The configuration of an eNB is the same asthat of an eNB in the first exemplary embodiment and so the descriptionis omitted here. In the description below, an MCE 301 is assumed to beconnected to one E-MBMS GW and multiple eNBs. The MCE 301 comprises anaverage traffic calculation unit 302 and a transmission mode controlunit 303.

The average traffic calculation unit 302 of the MCE 301 averagesreported values of PTP traffic volumes notified by respective eNBs andoutputs the averaged result as traffic information.

The transmission mode control unit 303 quantizes the PTP traffic volumesusing the traffic information and a table (not shown) that maps a PTPtraffic volume to one of the predetermined levels.

And, based on

MBMS control information;

a quantized traffic volume;

a PTP traffic volume prepared for each MBSFN outage probability (%);

MBSFN MCS and the number of MBSFN subframes; and

a table (not shown) indicating the relation of a transmission power orthe maximum of the transmission power in a reserved cell,

the transmission mode control unit 303 determines the transmissionparameters for use in the MBSFN area and transmits the MBMSconfiguration information to the E-MBMS GW, and the MBSFN controlinformation to eNBs.

FIG. 21 is a flowchart showing the processing of the MCE 301 in FIG. 20.

The MCE notifies base stations about default setting of the transmissionparameter of the MBSFN area and then waits for the base stations toreport the MBSFN related information including the PTP traffic volume.

If the control time, that is, the MBSFN area transmission parameterupdate time, has arrived before the MBSFN related information isreported to the average traffic calculation unit 302 (Yes in S304), thetransmission mode control unit 303 notifies the base stations about thedefault setting (or the most recent setting) (S305).

If the MBSFN related information is reported from the base stations (Yesin S301), the average traffic calculation unit 302 calculates a timeaverage of PTP traffic volume by performing a simple moving averaging ora weighted moving averaging, based on the included PTP traffic volumeinformation and PTP traffic volumes previously reported (S302).

And, the average traffic calculation unit 302 maps the PTP trafficvolume to one of the predetermined levels based on the time average ofthe PTP traffic volume and a mapping table created in advance forquantizing the PTP traffic volume (quantization) (S303).

Finally, the transmission mode control unit 303 checks if the controltime has arrived (S304) and, if the control time has arrived (Yes inS304), determines the MBSFN area transmission parameter, based on thePTP traffic volume index and the table, which is prepared in advance foreach MBSFN outage probability (%) to indicate the relation among the PTPtraffic volume, the MBSFN MCS, the number of MBSFN subframes, and thetransmission power or the maximum of transmission power in reservedcells, and notifies the base stations about the result.

The following describes the procedure for determining the MBSFN andunicast transmission parameters in the second exemplary embodiment.

In the description below, it is assumed that eNBA1-A3 and eNBB1-B2belong to the same MBSFN area and exchange information with the MCE,

eNBA1-A3 perform both unicast transmission and MBSFN transmission, and

eNBB1 and B2 perform only unicast transmission.

The MCE prepares in advance a table, such as the one shown in FIG. 22,for use in mapping the PTP traffic volume to one of several levels (Low,Medium, and High in FIG. 22). If the average PTP traffic is larger than0 but equal to or smaller than P1, the PTP traffic index is the value 0indicating “Low”; if the average PTP traffic is larger than P1 but equalto or smaller than P2, the PTP traffic index is the value 1 indicating“Medium”; and if the average PTP traffic is larger than P2, the PTPtraffic index is the value 2 indicating “High”.

In addition, the table such as the one shown in FIG. 23 is prepared inwhich the relation among the following is included.

PTP traffic indexes composed of reserved cell PTP traffic indexes andMBSFN service cell PTP traffic indexes;

transmission power or maximum of transmission power in reserved cells,

MBSFN MCS, and

Number of MBSFN subframes.

The values in the table in FIG. 23 are derived by Expression (1) so thatthe system throughput is maximized for an MBSFN outage probabilitytarget (for example, 10%) that is determined.

To use outage targets that are variable, tables are prepared for thetarget candidate values, one for each.

An eNB in the MBSFN area measures the PTP traffic volume at the periodTReport(=T) and notifies the MCE about the measurement result.

The average traffic calculation unit 302 of the MCE time-averages thePTP traffic volumes reported by eNBs in the MBSFN service cells and thePTP traffic volumes reported by eNBs in the reserved cells respectivelyand, using the table shown in FIG. 22, maps the averaged PTP trafficvolume to one of the levels defined in advance.

And, based on the mapped indexes of the PTP traffic volumes, thetransmission mode control unit 303 of the MCE, using the table shown inFIG. 23, at the period of Tctrl (for example, Tctrl=5*TReport=5T),determines the following:

MBSFN MCS;

Number of MBSFN subframes; and

Transmission power or the maximum of transmission power for MBSFNsubframes in reserved cells

For example,

when the PTP traffic index of the reserved cell is medium and

when the PTP traffic index of MBSFN service cells is low,

the transmission mode control unit 303 determines the following:

MBSFN MCS is 2;

the number of MBSFN subframes is 7; and

the transmission power or the maximum of transmission power for theMBSFN subframes in reserve cells is 80%.

The MCE notifies each eNB about the determined transmission parameters,and the eNB performs the MBSFN and unicast transmission according to thetransmission parameters.

Although the period Treport at which an eNB notifies the MCE about thePTP traffic volume and the period Tctrl at which the MCE notifies an eNBabout the transmission parameters are set individually in the presentembodiment, the same period may be used.

A trigger-based method may also be used in which the notification ismade when at least one or both satisfy the pre-defined condition.

In the above embodiment, interference to the MBSFN transmission isreduced by restricting the transmission power for the MBSFN subframes ina reserved cell.

If it is possible to select a band usable in the frequency domain as inOFDM (Orthogonal Frequency Division Mulitplex) which is the radio accessmethod employed by LTE, it is also possible to reduce interference byrestricting the frequency band (resource) usable for MBSFN subframes ina reserved cell, instead of, or in addition to, restricting thetransmission power.

Although, in the method described above, the MBSFN quality requirementis that the outage target value is satisfied while keeping the MBSFNtransmission rate constant, another method is also possible in whichonly the outage target value is satisfied, disregarding the MBSFNtransmission rate.

In this case, the MBSFN transmission rate may be decreased with priorityon an improvement in the PTP system throughput.

In addition, when the requirement is that only the MBSFN transmissionrate be kept constant and, under this condition, the PTP traffic volumein the reserved cells is increased, there is another control method inwhich the MBSFN coverage is reduced by using a larger MBSFN MCS and bydecreasing the number of MBSFN subframes.

Although the PTP traffic volume is used in the embodiments describedabove, the number of terminals performing PTP, or the number ofterminals in an active state in the cells, may also be used.

In addition to the PTP traffic volume or the number of terminals in anactive state,

the number of VoIP terminals,

the number of MBSFN receiving terminals or the estimated value of thenumber of MBSFN receiving terminals,

the number of MBSFN reception requesting terminals or the estimatedvalue of the number of MBSFN reception requesting terminals, or

the quality (error rate) of executing MBSFN, or the estimated value ofthe quality (error rate) of executing MBSFN

may be used or, instead of the PTP traffic volume or the number ofterminals in an active state, the ratio between the number of terminalsin an active state and the number of MBSFN receiving terminals may beused.

By causing all the MBSFN receiving terminals (or MBSFN receptionrequesting terminals) to report that they are receiving (or they arerequesting to receive) the MBSFN actually, or causing all the MBSFNreceiving terminals to report the received quality, the base station isable to obtain those numerical values. Note that the reports from allthe receiving terminals are not always necessary but that the reportsmay be received from terminals selected with a probability specified bythe base station or an upper-level equipment, in which case the basestation estimates the actual number of terminals from the number ofreceived reports (number of requests) and the probability. Thisestimation method is not limited by the most recent reports but the pastreports may be used in the estimation. The content of report may be anycontent as long as the fact that the terminals are receiving (orrequesting to receive) MBSFN transmissions, as well as its quality, isknown.

Although arranged on the periphery of the MBSFN service cells in theembodiments described above, the reserved cells need not always be onthe periphery but may be arranged in such a way that they are surroundedby multiple MBSFN service cells.

As the target values of the MBSFN service quality, not only the MBSFNoutage, the MBSFN coverage and the MBSFN service rate (transmissionrate) but also the received SIR (Signal-to-Interference) and thereceived SINR (Signal-to-Interference and Noise power Ratio) may beused.

In the embodiments described above, an example was described in whichthe MCE receives the multicast related information and the unicastrelated information from the eNBs in the MBSFN area as the communicationstatus information and in which the transmission parameters for theMBSFN area are determined as the communication control information. Itis also possible to determine cell parameters in the MBSFN area.

Although a 3GPP LTE system is assumed in the embodiments describedabove, the present invention is applicable also to other systems such as3GPP WCDMA (Wideband Code Division Multiple Access) or WiMAX (Worldwideinteroperability for Microwave Access). It is also apparent that thecommunication status information or the communication controlinformation is not limited to the MBSFN related information or thetransmission parameters but that the information on other transmissionmethods or services or the information on the radio resources used fornon-transmission applications may also be used.

The disclosure of the Non-Patent Document given above is herebyincorporated by reference into this specification. The embodiments andthe examples may be changed and adjusted in the scope of the entiredisclosure (including claims) of the present invention and based on thebasic technological concept. In the scope of the claims of the presentinvention, various disclosed elements may be combined and selected in avariety of ways. That is, it is to be understood that the presentinvention includes the modifications and changes that may be made bythose skilled in the art based on the entire disclosure including theclaims and on the technological concept.

1. A radio communication system comprising: a plurality of radiostations; and an apparatus that receives communication statusinformation from all or a part of said plurality of radio stations andoutputs communication control information for use in multicasting by aplurality of radio stations.
 2. The radio communication system accordingto claim 1, wherein said apparatus receives said communication statusinformation from a plurality of radio stations in an MBSFN (MultimediaBroadcast Multicast Service Single Frequency Network) area, and outputssaid communication control information on said MBSFN area, said MBSFNarea being an applicable area of MBSFN in which a plurality of radiostations are synchronized to transmit a same content with a samefrequency at a same time.
 3. The radio communication system according toclaim 2, wherein said communication status information includes at leastone of system component information, multicast related information, andunicast related information, and wherein said communication controlinformation includes at least one of a transmission parameter for saidMBSFN area, and a cell type of said MBSFN area.
 4. The radiocommunication system according to claim 2, wherein said MBSFN areaincludes a radio station that performs both MBSFN and unicast, and aradio station that does not contribute to MBSFN, and wherein saidapparatus outputs said communication control information for MBSFN by aradio station that is in said MBSFN area and that performs MBSFN, andsaid communication control information for a communication by a radiostation that is in said MBSFN area but that at a time when MBSFN isperformed, does not contribute to MBSFN.
 5. The radio communicationsystem according to claim 2, wherein said MBSFN area includes: a radiostation that performs both MBSFN and unicast, and a radio station thatdoes not contribute to MBSFN, and wherein said apparatus outputs saidcommunication control information for MBSFN in said MBSFN area.
 6. Theradio communication system according to claim 1, wherein said radiostation includes an MBSFN (Multimedia Broadcast Multicast Service SingleFrequency Network) function, and a unicast function, and wherein saidapparatus outputs said communication control information in said MBSFNarea, based on said system component information in said MBSFN area thatis said applicable range of MBSFN.
 7. The radio communication systemaccording to claim 6, wherein said apparatus collects, in addition tosaid system component information, at least one of multicast relatedinformation and unicast related information from all or a part of aplurality of radio stations in said same MBSFN area, and wherein saidapparatus outputs, as said communication control information, atransmission parameter for MBSFN in said MBSFN area, and/or, atransmission parameter for a communication that is performed by a radiostation, which is in said MBSFN area but does not contribute to MBSFN,and that is performed at said same time said MBSFN is performed.
 8. Theradio communication system according to claim 6, wherein as said systemcomponent information, one or more of the number of radio stations thatperform MBSFN, the number of areas served by a radio station thatperforms MBSFN, a size of an area served by a radio station thatperforms MBSFN, the number of radio stations that do not contribute toMBSFN, the number of areas served by a radio station that does notcontribute to MBSFN, and a size of an area served by a radio stationthat does not contribute to MBSFN is used.
 9. The radio communicationsystem according to claim 5, wherein as said multicast relatedinformation, one or more or of the number of terminals that arereceiving MBSFN or information that makes it possible to estimate thenumber of said terminals, the number of terminals that request toreceive MBSFN or information that makes it possible to estimate thenumber of said terminals, a quality of MBSFN being executed orinformation that makes it possible to estimate said quality, and a ratiobetween the number of terminals that are receiving MBSFN and the numberof terminals that are receiving unicast is used.
 10. The radiocommunication system according to claim 5, wherein as said unicastrelated information, one or more of a unicast traffic volume, the numberof terminals that are receiving unicast, the number of active terminalsthat may receive unicast, and the number of terminals that perform VoIP(Voice over Internet Protocol) is used.
 11. (canceled)
 12. The radiocommunication system according to claim 2, wherein at least one of a1) aunicast traffic volume in an MBSFN area, a2) the number of cellsconfiguring said MBSFN area, and a3) a radius of each cell configuringsaid MBSFN area is received from said radio station, as saidcommunication status information and, b) while satisfying an MBSFNrequirement, in order to implement at least one of c1-c4 c1) increasinga unicast system throughput in said MBSFN area, c2) enabling an MBSFNcoverage to be maintained constant, c3) enabling an MBSFN transmissionrate to be maintained constant, and c4) enabling an MBSFN service rateto be maintained constant, at least one of d1-d10 d1) an MBSFN MCS(Modulation and Coding Scheme), d2) the number of MBSFN subframes, d3)an MBSFN subframe position d4) an MBSFN frame position d5) an MBSFNframe period d6) a transmission power or a maximum of said transmissionpower of a communication that is performed by a radio station, whichdoes not contribute to MBSFN, and that is performed at said same timeMBSFN is performed, d7) a frequency usage rate of a communication thatis performed by a radio station, which does not contribute to MBSFN, andthat is performed at said same time MBSFN is performed, d8) a frequencyresource of a communication that is performed by a radio station, whichdoes not contribute to MBSFN, and that is performed at said same timeMBSFN is performed, d9) an MBSFN reference signal, and d10) an MBSFNscrambling code is output, as said communication control information e1)periodically or e2) based on a predetermined trigger.
 13. (canceled) 14.(canceled)
 15. (canceled)
 16. The radio communication system accordingto claim 2, wherein MBSFN and unicast are multiplexed, in a time domain,on a per subframe basis, said frame being composed of N subframes (N isa predetermined positive integer), and wherein in allocating a radioresource used for said MBSFN, at least one of a subframe number used forMBSFN, a start subframe number and the number of subframes to be used,the number of a frame used for MBSFN or information indicating thenumber of said frame, and a frame period at which MBSFN is performed isused.
 17. (canceled)
 18. The radio communication system according toclaim 2, wherein MBSFN and unicast are multiplexed in a frequencydomain, and wherein as an allocation of a radio resource used for saidMBSFN, a position of continuous or discontinuous frequency resource isused.
 19. The radio communication system according to claim 2, whereinas transmission parameters for said unicast that is performed at saidsame time MBSFN is performed, at least one of a transmission power or amaximum of said transmission power, a frequency usage rate, and afrequency resource, is used.
 20. (canceled)
 21. (canceled)
 22. A basestation apparatus that includes an MBSFN (Multimedia Broadcast Multicastservice Single Frequency Network) function that causes said base stationapparatus to synchronize with one or more other base station apparatusesto transmit a same content with a same frequency at a same time and aunicast function, said apparatus comprising: a unit that notifies aMulti-cell/Multicast Coordination Entity (MCE) apparatus aboutcommunication status information, and a unit that receives communicationcontrol information from said Multi-cell/Multicast Coordination Entityapparatus to perform MBSFN or unicast or single-cell/multicasttransmission.
 23. A base station apparatus that includes an MBSFN(Multimedia Broadcast multicast service Single Frequency Network)function that causes said base station apparatus to synchronize with oneor more other base station apparatuses to transmit a same content to aplurality of terminals with a same frequency at a same time and aunicast function, characterized in that said apparatus comprising: aunit that measures information in an MBSFN area that is an applicablearea of MBSFN, said information in an MBSFN area including at least oneof the number of terminals that are receiving MBSFN or information thatmakes it possible to estimate the number of said terminals, the numberof terminals that request to receive MBSFN or information that makes itpossible to estimate the number of said terminals, a unicast trafficvolume, the number of terminals that are receiving unicast, the numberof active terminals that may receive unicast, a ratio between the numberof terminals that are receiving MBSFN and the number of terminals thatare receiving unicast, the number of terminals that perform VoIP (Voiceover Internet Protocol), and a quality of MBSFN being executed orinformation that makes it possible to estimate said quality; a unit thatnotifies, either periodically or upon occurrence of a pre-specifiedevent, a Multi-cell/Multicast Coordination Entity (MCE) apparatus, whichoutputs a transmission parameter for an MBSFN area, about said measuredresult; and a unit that performs communication, based on saidtransmission parameter received from said Multi-cell/MulticastCoordination Entity apparatus, said transmission parameter prepared forat least one of MBSFN and a communication performed at said same timewhen said MBSFN is performed.
 24. A Multi-cell/Multicast CoordinationEntity (MCE) apparatus that outputs communication control information inMBSFN (Multimedia Broadcast Multicast service Single Frequency Network)in which a plurality of base station apparatuses are synchronized totransmit said same content with a same frequency at a same time, saidMulti-cell/Multicast Coordination Entity (MCE) apparatus comprising: aunit that receives communication status information from a base stationapparatus in an MBSFN area, which is an applicable range of MBSFN; and aunit that notifies said base station apparatus about said communicationcontrol information.
 25. The Multi-cell/Multicast Coordination Entityapparatus according to claim 24, further comprising a unit that receivesinformation in an MBSFN area, which is an applicable range of MBSFN,from a base station apparatus as said communication status information,said information in an MBSFN area including at least one of the numberof terminals that are receiving MBSFN or information that makes itpossible to estimate the number of said terminals, the number ofterminals that request to receive MBSFN or information that makes itpossible to estimate the number of said terminals, a unicast trafficvolume, the number of terminals that are receiving unicast, the numberof active terminals that may receive unicast, a ratio between the numberof terminals that are receiving MBSFN and the number of terminals thatare receiving unicast, the number of terminals that perform VoIP (Voiceover Internet Protocol), and a quality of MBSFN being executed orinformation that makes it possible to estimate said quality; a unit thatbased on said communication status information received from said basestation apparatus, determines, either periodically or upon occurrence ofa pre-specified event, a transmission parameter for at least one ofMBSFN and a communication that is performed at said same time said MBSFNis performed; and a unit that notifies said base station apparatus aboutsaid transmission parameter as said communication control information.26. A radio communication method, comprising: receiving communicationstatus information from all or a part of a plurality of radio stations;and outputting communication control information for use in multicastingby a plurality of radio stations.
 27. The radio communication methodaccording to claim 26, further comprising: receiving said communicationstatus information in an MBSFN (Multimedia Broadcast Multicast ServiceSingle Frequency Network) area; and outputting said communicationcontrol information in said MBSFN area, said MBSFN area being anapplicable range of MBSFN in which a plurality of radio stations aresynchronized to transmit said same content with a same frequency at asame time.
 28. The radio communication method according to claim 27,wherein said communication status information includes at least one ofsystem component information, multicast related information, and unicastrelated information, and wherein said communication control informationincludes at least one of transmission parameters for said MBSFN area anda cell type of said MBSFN area.
 29. The radio communication methodaccording to claim 27, wherein said MBSFN area includes a radio stationthat performs both MBSFN and unicast, and a radio station that does notcontribute to MBSFN, and wherein said communication control informationfor MBSFN by said radio station that is in said MBSFN area and thatperforms MBSFN, and said communication control information for acommunication by said radio station that is in said MBSFN area but that,when MBSFN is performed, does not contribute to MBSFN are output. 30.(canceled)
 31. A computer-readable recording medium storing a programthat causes a computer to perform the processing comprising: receivingcommunication status information from all or a part of a plurality ofradio stations; and outputting communication control information for usein multicasting by a plurality of radio stations.
 32. Thecomputer-readable recording medium according to claim 31, storing aprogram causing said computer to perform the processing comprising:receiving said communication status information in an MBSFN (MultimediaBroadcast Multicast Service Single Frequency Network) area; andoutputting said communication control information in said MBSFN area,said MBSFN area being an applicable range of MBSFN in which a pluralityof radio stations are synchronized to transmit said same content with asame frequency at a same time.
 33. A radio communication methodcomprising: a) preparing a table in a Multi-cell/Multicast CoordinationEntity (MCE) apparatus, said table including a unicast traffic volumeand at least one of an MCS (Modulation and Coding Scheme) of MBSFN(Multimedia Broadcast multicast service Single Frequency Network), thenumber of MBSFN subframes, and a transmission power or a maximum of saidtransmission power of a base station in a reserved cell; b) a basestation in an MBSFN area transmitting a unicast traffic volume of a cellthereof to said Multi-cell/Multicast Coordination Entity apparatus,either periodically or upon occurrence of a predetermined trigger; c)said Multi-cell/Multicast Coordination Entity apparatus receiving saidunicast traffic volume from said base station in said MBSFN area and,with reference to said table and based on said received traffic volume,selecting at least one of a modulation and coding scheme of MBSFN, thenumber of MBSFN subframes, and a transmission power or a maximum of saidtransmission power of a base station in a reserved cell; d) saidMulti-cell/Multicast Coordination Entity apparatus transmitting at leastone of the number of MBSFN subframes, and said modulation and codingscheme of MBSFN to an MBSFN service cell, and transmitting at least oneof the number of MBSFN subframes, and said transmission power or saidmaximum of said transmission power of a base station in a reserved cellto a reserved cell; and e) said base station setting a transmissionparameter according to configuration information from saidMulti-cell/Multicast Coordination Entity apparatus.
 34. A radiocommunication method comprising: in multi-cell transmission, aMulti-cell/Multicast Coordination Entity (MCE) apparatus collectingmulticast related information and/or unicast related information fromall or a part of base stations in said same MBSFN area; and saidMulti-cell/Multicast Coordination Entity apparatus outputting atransmission parameter for use in said MBSFN area.
 35. The radiocommunication method according to claim 34, wherein said multicastrelated information includes at least one of the number of terminalsreceiving/requesting to receive MBMS/MBSFN and an error rate ofMBMS/MBSFN, wherein said unicast related information includes at leastone of the number of terminals in a radio link established state(RRC_CONNECTED), the number of VoIP (Voice over Internet) terminals, anda point-to-point traffic volume, wherein said multicast and unicastrelated information includes a ratio between the number of terminalsthat are receiving multicast services and the number of terminal thatare receiving unicast services, and wherein said Multi-cell/MulticastCoordination Entity apparatus outputs a transmission parameter for MBSFNand/or unicast in said MBSFN area, said transmission parameter for MBSFNincluding at least one of the number of MBSFN subframes and MSAP(Multicast channel Subframe Allocation Pattern) that indicates amicro/macro level allocation of MBSFN subframes, an MCS (Modulation andCoding Scheme), and a maximum transmission power, and said transmissionparameters for unicast includes a maximum transmission power and/or afrequency resource usable for unicast in a reserved cell in said MBSFNarea.
 36. A Multi-cell/Multicast Coordination Entity (MCE) apparatuscomprising: a unit that receives, from a base station in an MBSFN(Multimedia Broadcast Multicast Service Single Frequency network) area,a unicast traffic volume of a cell thereof; a unit that determines atransmission parameter that include at least one of an MBSFN modulationand coding scheme, the number of MBSFN subframes, and a transmissionpower or a maximum of said transmission power of a base station in areserved cell, while satisfying an MBSFN quality requirement, based onat least one of a unicast traffic volume in an MBSFN area, the number ofterminals, and the number of cells of said MBSFN area; a unit thattransfers at least one of the number of MBSFN subframes, and said MBSFNmodulation and coding scheme to an MBSFN service cell; and transfers atleast one of the number of MBSFN subframes and said transmission poweror said maximum of said transmission power of a base station in areserved cell to a reserved cell.
 37. (canceled)
 38. The radiocommunication system according to claim 4, wherein said communicationcontrol information is output by a Multi-cell/Multicast CoordinationEntity (MCE) apparatus.